<template>
    <div>
        <router-link
            tag="div" 
            to="/" 
            class="header-abs"
            v-show="showAbs"
        >
            <div class="iconfont header-abs-back">&#xe624;</div>
        </router-link>
        <div
            class="header-fixed"
            v-show="!showAbs"
            :style="opacityStyle"
        >
            <router-link to="/">
                <div class="iconfont header-fixed-back">&#xe624;</div>
            </router-link>
            {{this.sightName}}
        </div>
    </div>
</template>

<script>
export default {
    name: 'DetailHeader',
    props: {
        sightName: String
    },
    data () {
        return {
            showAbs: true,
            opacityStyle: {
                opacity: 0
            }
        }
    },
    methods: {
        handleScroll () {
            const top = document.documentElement.scrollTop || document.body.scrollTop
            if (top > 60) {
                let opacity = top/140
                opacity = opacity >1 ? 1 : opacity
                this.opacityStyle = {
                    opacity
                }
                this.showAbs = false
            } else {
                this.showAbs = true
            }
        }
    },
    mounted () {
        window.addEventListener('scroll', this.handleScroll)
    }
    // 由于Detail页面被exclude了，所以activated 和 deactivated 事件将不会被触发
    // activated () {
    //     console.log("activated")
    //     window.addEventListener('scroll', this.handleScroll)
    // },
    // deactivated () {
    //     window.removeEventListener('scroll', this.handleScroll)
    // }
}
</script>

<style lang="stylus" scoped>
    @import '~styles/varibles.styl'
    .header-abs
        position: absolute
        top: .2rem
        left: .2rem
        width: .8rem
        height: .8rem
        line-height: .8rem
        border-radius: .4rem
        background: rgba(0,0,0,.8)
        text-align: center
        .header-abs-back
            color: #fff
            font-size: .4rem
    .header-fixed
        z-index: 2
        position: fixed
        top: 0
        left: 0
        right: 0
        height: $headerHeight
        line-height: $headerHeight
        text-align: center
        color: #fff
        background: $bgColor
        font-size: .32rem
        .header-fixed-back
            position: absolute
            top: 0
            left: 0
            width: .64rem
            text-align: center
            font-size: .4rem
            color: #fff

</style>
